A Study to Evaluate the Safety, Tolerability, PK, PD, and Clinical Activity of EQ001 in Subjects With aGVHD

This is a multi-center study to evaluate the safety, tolerability, PK, PD, and clinical activity of EQ001 in subjects with Acute Graft Versus Host Disease (aGVHD).

Inclusion Criteria: 1. Male or female subject at least 18 years of age for Part A, and at least 12 years of age for Part B. 2. Recipients of allogeneic hematopoietic stem cell transplantation (alloHSCT) using myeloablative or non myeloablative conditioning regimens. 3. Have a clinical diagnosis of acute GVHD requiring systemic immune suppressive therapy. 4. Deemed by the investigator to be likely to comply with the planned procedure as required by the protocol for the duration of the study Exclusion Criteria: 1. Presence of morphologic relapsed primary malignancy, treatment for relapse after alloHSCT was performed, or requirement for rapid immunosuppressive treatment withdrawal for early malignancy relapse. 2. Evidence of graft failure based on cytopenia(s), and as determined by the investigator. 3. Evidence of post-transplant lymphoproliferative disease. 4. Any prior therapy for acute GVHD, except for alloHSCT prophylaxis regimens or systemically administered corticosteroids. 5. As determined by the investigator, any medical, psychiatric, or other condition or circumstance that is likely to negatively affect: the subject's participation in this clinical study, the subject's safety, or the reliability of the study data.